Tamperproof plastic container

ABSTRACT

A container (10) is disclosed as including a receptacle (12), a cover (14), and a tether (16) that are molded from plastic unitary with each other with the receptacle and cover connected by the tether. Downward cover movement over the receptacle provides a snap action engagement of locking surfaces on mating helical threads (30) and (32) of the receptacle and cover in order to prevent opening movement of the cover without unthreading rotation. The tether (16) has a length that is sufficiently long to permit the initial cover closing and sufficiently short to limit unthreading rotation of the closed cover for opening with the tether intact. Tether (16) is frangible by either cutting with a knife or scissors, etc. or by breaking upon the application of unthreading cover rotation to thereby provide a visual indication of the cover opening in order to render the container tamperproof.

This is a continuing application of copending application Ser. No.688,002 which was filed on Dec. 31, 1984 and issued on Oct. 22, 1985 asU.S. Pat. No. 4,548,332.

TECHNICAL FIELD

This invention relates to a plastic container that has a tamperproofconstruction and thus has particular utility for packaging food,pharmaceuticals and the like, but which may also be utilized to holdother goods such as paint, varnish, and stain, etc. where it is likewisedesirable to know whether the container has been initially opened.

BACKGROUND ART

Prior art plastic containers have included a unitary receptacle and aunitary cover that are secured to each other to close the container.Securement constructions previously utilized to securely hold the coveron the receptacle have not permitted easy opening and closing whilestill maintaining the cover securely closed on the receptacle. Also,there has not been any prior tamperproof design constructed as anintegral part of a plastic container which has received any significantcommercial acceptance.

Paint, varnish, stain and the like are conventionally sold at the retaillevel in metal cans which have an upper edge with a groove in which anannular edge of a metal cover is secured by a press fit. Opening of thecover is performed by prying the cover edge upwardly out of engagementwith the can edge so that the stored contents can be used. Such metalcans are conventionally made from tin plated steel which has become moreand more expensive in the recent past. Also, the ever increasing use ofwater-based latex paint with steel cans has necessitated the use of aspecial coating on the interior of the can in order to prevent the waterfrom causing corrosion as the paint is stored. Another problem withmetal paint cans is that they tend to dent when struck or dropped.

One prior attempt at making paint cans from other than metal utilizedinjection or blow molding of polypropylene plastic in order to overcomethe corrosion problem when water-based latex paints are stored. This canrequire a molded bead on the inner surface at the upper end of the canin order to secure an associated cover with the required strengthnecessary to pass drop tests paint cans are subjected to before beingaccepted commercially by paint manufacturers.

U.S. Pat. Nos. 3,998,355 and 4,126,246 disclose plastic lids and pailswhich are secured to each other by engagement threads each of whichextends about one-quarter of the circumference of the lid or pail. Thesize of the pails disclosed is relatively large, on the order of thatrequired to hold five gallons of liquid or so. To date, this type ofcontainer has not found any widespread commercial acceptance as a paintcontainer in the retail market. This lack of acceptance is probably aresult of the fact that the pail wall thickness and cover wall thicknessnecessary to maintain engagement of the threads is so great as to makethe construction impractical for paint containers which are normallysold at the retail level in a one gallon size or smaller. Also, thecover can only be secured to the pail by threading due to the cover,receptacle and thread construction involved.

U.S. Pat. Nos. 4,245,753 and 4,245,754 disclose plastic containers forpaint wherein segmented buttress retainers secure a cover to areceptacle for storage while permitting removal of the cover uponrotation and subsequent upward movement. With this type of construction,the locations between the buttress retainers result in a spacedrelationship between a side wall of the receptacle and an annular lip ofthe cover on which the segmented buttress retainers are supported. Suchspacing between the receptacle side wall and the cover lip allowsdeflection therebetween in a manner that can disengage the buttressretainers such that opening of the cover can result in certain instanceswhen the container is dropped.

My prior U.S. Pat. No. 4,453,647 discloses an improved plastic containerhaving a receptacle and a cover which can be securely attached to eachother by either threading rotation of the cover or downward covermovement onto the receptacle. The cover of this container can also beeasily detached from the receptacle by unthreading rotation of the coverwith respect to the receptacle. Such secure attachment of the cover tothe receptacle is provided by at least one retainer on either thereceptacle or the cover and is preferably provided by a retainer on boththe receptacle and the cover. Each retainer has an annular shape andopens vertically, with the retainer of the receptacle opening upwardly,and with the retainer of the cover opening downwardly. Upon closing ofthe cover, the retainer of the receptacle receives the lower round edgeof an annular lip on the cover and the retainer of the cover receives around upper edge of the receptacle side wall to thereby maintainengagement of helical threads on the cover lip and the receptacle sidewall. While this container construction securely holds the cover closedon the receptacle, there is no provision to prevent tampering of theclosed container after filling with whatever goods are to be held by thecontainer.

DISCLOSURE OF INVENTION

An object of the present invention is to provide an improved plasticcontainer having a receptacle and a cover which can be securely attachedto each other with a tamperproof construction that provides thecontainer with particular utility for packaging food, pharmaceuticalsand the like while also having use in holding other goods such as paint,varnish, and stain as well as anything else for which it is desirable toknow whether the container has been initially opened.

In carrying out the above object, the container includes a receptacle, acover, and a tether that are molded from plastic unitary with each otherwith the receptacle and cover connected by the tether. The receptacle ofthe container has a lower closed end and also has a round upper end thatopens upwardly. The cover of the container includes an upper wall and anannular lip that extends downwardly from the upper wall. Mating helicalthreads are provided on the upper end of the receptacle and the annularlip of the cover. These threads have slide surfaces that are slidablyengaged with each other by an initial downward movement of the coverover the receptacle. The threads also have locking surfaces that areengaged by each other by snap action upon continued downward covermovement to secure the cover in a closed position and prevent upwardopening movement thereof without unthreading rotation of the cover withrespect to the receptacle. In constructing the container, the tether isprovided with a length that is sufficiently long to permit the initialcover closing and sufficiently short to limit unthreading rotation ofthe closed cover in order to prevent opening thereof with the tetherintact connecting the receptacle and the cover. The construction of thetether is frangible to permit unthreading rotation of the cover foropening while also providing a visual indication of such opening tothereby render the container tamperproof.

In the preferred construction of the container constructed in accordancewith the invention, the round upper end of the receptacle includes aretainer that prevent separating horizontal movement between the helicalthreads with the cover closed to thereby assist in the prevention ofopening of the container cover with the tether intact. The round upperend of the receptacle also preferably includes a seal and the cover hasa seal surface that engages the receptacle seal with the cover closed toseal the container. The preferred construction of the cover alsoincludes a retainer that engages the upper end of the receptacleadjacent the seal and assists in preventing horizontal separatingmovement between the helical threads with the cover closed to therebyprevent opening of the container cover with the tether intact. Thelocking surfaces of the helical threads are preferably inclined tosecure the helical threads against separating movement in cooperationwith the retainer securement.

In the preferred construction, the tether has an elongated shape whosecross section may be a thin band, round, oval, square or any othersuitable configuration. Upon opening, the elongated tether may eitherfracture by the opening rotational force imparted to the cover or mayrequire cutting by a knife or scissors depending upon the plasticutilized and the size and shape of the tether cross section. The firstend of the elongated tether is preferably integrally connected to thereceptacle at its upper end, and the second end of elongated tether ispreferably integrally connected to the cover at its annular lip.

The length of the elongated tether is most preferably short enough torequire that the ends thereof be circumferentially aligned with respectto the container to permit the cover positioning over the receptacle forthe downward closing movement with the tether intact. Also, the helicalthreads on the upper end of the receptacle and the annular lip of thecover are positioned such that, during downward closing movement, thecover must be rotated in an unthreading direction with respect to thereceptacle to provide the snap action engagement of the locking surfacesthat secures the cover closed. The extent of the cover unthreadingmovement during closing is of an extent that makes the tether taut tothereby prevent partial opening rotation of the cover with the tetherintact. As such, tampering with the container is prevented.

To assist in opening the closed cover, the receptacle and the annularlip of the cover are preferably provided with opening assist lugs thatare positioned adjacent each other in the closed position. These openingassist lugs permit a pry to be utilized to rotate the cover in anunthreading direction with respect to the receptacle for opening and mayassist in the initial fracturing of the tether during such opening.

The objects, features, and advantages of the present invention arereadily apparent from the following detailed description of the bestmode for carrying out the invention when taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an elevation view taken in section through a container whichincludes a receptacle, a cover, and a tether constructed in accordancewith the present invention to provide tamperproof closing;

FIG. 2 is a top plan view of the container taken along the direction ofline 2--2 in FIG. 1;

FIG. 3 is a partial sectional view taken through the container in thesame direction as FIG. 1 but showing the cover positioned over thereceptacle in preparation for downward closing movement;

FIG. 4 is an enlarged, partial sectional view of the container after aninitial downward movement that engages slide surfaces on helical threadsof an upper end of the receptacle and a downwardly projecting annularlip of the cover;

FIG. 5 is a view similar to FIG. 4 after the cover has been moved to afully closed position where locking surfaces of the threads are engagedby a snap action;

FIG. 6 is a partial elevation view of the container taken along thedirection of line 6--6 in FIG. 3 but with the cover closed to illustratethe orientation of the tether prior to the initial opening movement ofthe cover;

FIG. 7 is a partial elevation view of the container taken along thedirection of line 7--7 in FIG. 6 and illustrates opening assist lugs onthe receptacle and cover which are utilized in association with a pry inorder to provide the initial unthreading movement of the cover foropening; and

FIG. 8 is a partial elevation view taken in the same direction as FIG. 6and illustrates the fractured condition of the tether upon the initialunthreading movement of the cover for opening.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to FIGS. 1 and 2 of the drawings, a container constructedin accordance with the present invention is generally indicated by 10and includes a receptacle 12, a cover 14, and a tether 16 that aremolded from plastic unitary with each other with the receptacle andcover connected by the tether. Any suitable semirigid plastic ispreferably utilized such as high density polyethylene, polypropylene, orpolyethylene terephthalate, etc. Receptacle 12 has a lower closed end 18that is cooperatively defined by a lower end of a receptacle side wall20 and a bottom wall 22 which is illustrated as having a slightlyupwardly projecting curved shape so as to provide an annular lowersupport surface 23 for the receptacle. Receptacle 12 also has a roundupper end 24 that is defined by an upper end of the side wall 20 andopens upwardly with a wide mouth construction of the maximum diameter ofthe receptacle. As illustrated by FIG. 3, the cover 14 in its normal useorientation includes an upper wall 26 and also includes an annular lip28 that extends downwardly from the upper wall at its outer periphery.

As best illustrated in FIGS. 4 and 5, mating helical threads 30 and 32are provided on the upper receptacle end 24 and the annular lip 28 ofthe cover, respectively. These helical threads 30 and 32 have associatedslide surfaces 30a and 32a that are slidably engaged with each other asillustrated in FIG. 4 by an initial downward movement of the cover overthe receptacle. Helical threads 30 and 32 also have associated lockingsurfaces 30b and 32b that are engaged with each other as illustrated inFIG. 5 by a snap action upon continued downward cover movement. Thissnap action takes place as the upper end of the receptacle side wall 20and the annular cover lip 28 flex to permit the downward cover movementfrom the position of FIG. 4 to the position of FIG. 5 as the coverthread 32 moves downwardly below the receptacle thread 30. Engagement ofthe locking surfaces 30b and 32b as illustrated in FIG. 5 secures thecover 14 in a closed position on the receptacle 12 and prevents upwardopening movement thereof without unthreading rotation of the cover withrespect to the receptacle.

As illustrated in FIG. 3, the tether 16 has a length that issufficiently long to permit the cover 14 to be positioned over thereceptacle 12 for the initial cover closing. Tether 16 also has a lengththat is sufficiently short to limit threading rotation of the closedcover in order to prevent opening thereof with the tether intactconnecting the receptacle and the cover. Tether 16 is frangible bycutting with a knife or scissors or by breaking as result of unthreadingrotational force applied to the cover. Such fracturing of the tether 16as illustrated in FIG. 8 permits unthreading rotation of the cover 14for opening while also providing a visual indication of the opening tothereby render the container tamperproof.

The tamperproof feature provided by the unitary receptacle 12, cover 14,and tether 16 provides the container 10 with particular utility whenutilized to package food, pharmaceuticals and the like. In addition,other goods, such as paint, varnish, and stain, etc. can also bepackaged by the container to advantageously provide an indication ofwhether the container has been initially opened. This allows a storeowner to make a determination whether a retail customer has returned thecontainer unopened such that an exchange or refund should be permitted.

As best illustrated in FIGS. 3, 4, and 5, the preferred construction ofthe container 10 also has the round upper end 24 of the receptacleprovided with a retainer 34 on the outer surface of the receptacle sidewall 20. This retainer 34 receives the round lower edge 36 of theannular cover lip 28 in the closed position of the cover illustrated byFIG. 5. After the flexing of the receptacle side wall 20 and the coverlip 28 to provide the snap action closing previously described, theretainer 34 assists in prevention of separating horizontal movementbetween the helical threads 30 and 32 to thereby prevent opening of thecontainer cover 14 with the tether intact. An annular rib 38 of thecover lip 28 is located just above the retainer 34 in the closed coverposition and inhibits prying or other attempted tampering with thecontainer. It should also be noted that other retainer constructions canbe utilized such as illustrated in my aforementioned U.S. Pat. No.4,453,647, the entire disclosure of which is hereby incorporated byreference.

As best illustrated in FIG. 4, the round upper end 24 of the receptacleincludes a seal 40 that is preferably provided with a taperedconfiguration inclined upwardly in an outward direction. Cover 14 has anannular seal surface 42 that engages the receptacle seal 40 to seal thecontainer as the cover is moved to the closed position illustrated inFIG. 5. The cover 14 also preferably includes a retainer 44 at theperiphery of its upper wall 26 from which the annular cover lip 28projects downwardly. This cover retainer 44 engages the upper end of thereceptacle side wall 20 just below the seal 40 as illustrated in FIG. 5to assist in the prevention of separating horizontal movement betweenthe helical threads 30 and 32 with the cover closed.

Receptacle retainer 34 and cover retainer 44 cooperate as describedabove to maintain the helical thread engagement and thereby preventopening of the cover with the tether intact. Locking surfaces 30b and32b of the helical threads are preferably inclined in a reversedirection that secures the helical threads against separating movementin cooperation with the retainer securement. It will be noted that thelower edge 36 of the cover lip 28 has a slight spacing from the lowertrough defined by the receptacle retainer 34 in order to initiallypermit the downward cover movement to a slightly greater extent thanthat shown as the inclined locking surfaces are moved past each otherfor the snap action engagement upon closing. Seal 40 also flexes to aslightly greater extent than that shown by the initial downward covermovement as the cover seal surface 42 initially moves downwardly topermit the inclined locking surfaces 30b and 32b of the threads to movepast each other for the snap action engagement as previously described.Other interlocking configurations of the threads can also be used, suchas the hook shape shown by my previously mentioned U.S. Pat. No.4,453,647 which has been incorporated herein by reference. However, theinclined locking surfaces of the threads are the preferred construction.

As illustrated in FIGS. 1 and 2, tether 16 has an elongated shape whoselength is much greater than any of its cross-sectional dimensions so asto be flexible in all directions like a cord. A first end 46 of tether16 is integrally connected to the receptacle 12 and a second end 48thereof is integrally connected to the cover 14. An intermediate portion50 of the tether 16 has an elongated shape interconnecting the first andsecond ends 46 and 48 and may have any of the cross sections previouslydescribed. In the preferred construction illustrated, the first end 46of the elongated tether 16 is integrally connected to the upper end 24of the receptacle 12 at its retainer 34 previously described. Also, thesecond end 48 of the elongated tether 16 is integrally connected to thecover 14 at the outer surface of its annular lip 28.

Best results are achieved when the length of the tether 16 is shortenough to require that the ends 46 and 48 thereof be circumferentiallyaligned with respect to the container as illustrated in FIG. 3 in orderto permit the cover 14 to be positioned over the receptacle 12 fordownward closing movement with the tether intact. Upon initial downwardmovement of the cover 14 for closing, the tether 16 begins to slacken.However, the helical threads 30 and 32 on the upper end 24 of thereceptacle and on the annular lip 28 of the cover are positioned suchthat the cover during the downward closing movement must be rotated inan unthreading direction with respect to the receptacle to provide thesnap action engagement of the thread locking surfaces that secures thecover closed. If such unthreading rotation of the cover is not performedduring the downward closing movement, the slide surfaces 30a and 32a ofthe threads will remain in engagement with each other without permittingthe snap action closing that engages the thread locking surfaces 30b and32b. The extent of the cover unthreading movement during closing is ofan extent that makes the tether 16 taut as illustrated in FIG. 6 tothereby prevent partial opening rotation of the cover with the tetherintact.

As illustrated in FIGS. 2, 6, and 7, the upper end 24 of the receptacleand the annular lip 28 of the cover are provided with associated openingassist lugs 52 and 54. These opening assist lugs 52 and 54 arepositioned adjacent each other in the closed position of the cover asshown in FIG. 7 to permit a pry such as the curved end of a can opener56 to be positioned between the lugs for the application of unthreadingforce to the cover. The force applied by the pry 56 may be used tofracture the tether 16 or such fracturing may be provided by cutting thetether with a knife or scissors as previously discussed. Usually, thefracture will be at the elongated intermediate portion 50 of the tether16 as illustrated at 58 in FIG. 8. However, it is also possible for thefracture to be at one of the ends 46 or 48 of the tether 16. Upon thefracturing in whatever way and at whichever location, the tether 16breaks to provide the visual indication that renders the containertamperproof.

While the best mode for carrying out the invention has been described indetail, those familiar with the art to which this invention relates willrecognize various alternative designs and embodiments for practicing theinvention as defined by the following claims.

What is claimed is:
 1. A container comprising: a receptacle, a cover, and a tether that are molded from plastic unitary with each other with the receptacle and cover connected by the tether; said receptacle having a lower closed end and also having a round upper end that opens upwardly; locking means on the upper end of the receptacle and the cover; said locking means having locking surfaces that are engaged with each other upon downward cover movement to secure the cover in a closed position on the receptacle and prevent upward opening movement; the locking surfaces being disengaged from each other upon rotation of the cover with respect to the receptacle to provide opening; the tether having a length that is sufficiently long to permit the initial cover closing and sufficiently short to limit rotation of the closed cover in order to prevent opening thereof with the tether intact connecting the receptacle and the cover; and the tether being frangible to permit rotation of the cover for opening while also providing a visual indication of such opening to thereby render the container tamperproof.
 2. A container as in claim 1 wherein the round upper end of the receptacle includes a retainer that prevents separating horizontal movement of the locking means on the upper end of the receptacle and the cover to thereby assist in the prevention of opening of the container cover with the tether intact.
 3. A container as in claim 1 or 2 wherein the round upper end of the receptacle includes a seal, the cover having a seal surface that engages the receptacle seal with the cover closed to seal the container, and the cover including a retainer that engages the upper end of the receptacle adjacent the seal and prevents separating horizontal movement of the locking means on the upper end of the receptacle and the cover to thereby assist in the prevention of opening of the container cover with the tether intact.
 4. A container as in claim 3 wherein the locking surfaces of the locking means are inclined to prevent separating movement thereof in cooperation with the retainer securement.
 5. A container as in claim 1 wherein the tether has an elongated shape including a first end integrally connected to the receptacle and a second end integrally connected to the cover.
 6. A container as in claim 5 wherein the first end of the elongated tether is integrally connected to the upper end of the receptacle, and the cover having an annular lip to which the second end of the elongated tether is integrally connected.
 7. A container as in claim 5 or 6 wherein the tether has a length that is short enough to require that the ends thereof be circumferentially aligned with respect to the container to permit the cover positioning over the receptacle for the downward closing movement with the tether intact.
 8. A container as in claim 1, 2, 5, or 6 wherein the upper end of the receptacle and the cover include opening assist lugs.
 9. A container comprising: a receptacle, a cover, and a tether that are molded from plastic unitary with each other with the receptacle and cover connected by the tether; said receptacle having a lower closed end and also having a round upper end that opens upwardly; the cover including an upper wall and an annular lip that extends downwardly from the upper wall; locking means on the upper end of the receptacle and the annular lip of the cover; said locking means including locking surfaces that are engaged with each other upon downward movement of the cover to secure the cover in a closed position on the receptacle; the locking surfaces being disengaged from each other upon rotation of the cover with respect to the receptacle to provide opening; the round upper end of the receptacle and the cover having associated retainers that cooperate to prevent separating horizontal movement of the locking means on the upper end of the receptacle and the annular lip of the cover; the tether having a length that is sufficiently long to permit the initial cover closing and sufficiently short to limit opening rotation of the closed cover in order to prevent opening thereof with the tether intact connecting the receptacle and the cover; and the tether being frangible to permit opening rotation of the cover while also providing a visual indication of such opening to thereby render the container tamperproof.
 10. A container comprising: a receptacle, a cover, and a tether that are molded from plastic unitary with each other with the receptacle and cover connected by the tether; said receptacle having a lower closed end and also having a round upper end that opens upwardly; the cover including an upper wall and an annular lip that extends downwardly from the upper wall; locking means on the upper end of the receptacle and the annular lip of the cover; said locking means including locking surfaces that are engaged with each other upon downward movement of the cover to secure the cover in a closed position on the receptacle; the locking surfaces being disengaged from each other upon rotation of the cover with respect to the receptacle to providing opening; the round upper end of the receptacle and the cover having associated retainers that cooperate to prevent separating horizontal movement of the locking means on the upper end of the receptacle and the annular lip of the cover; the tether having an elongated shape including a first end integrally connected to the upper end of the receptacle and having a second end integrally connected to the annular lip of the cover; the tether having a length that is sufficiently long to permit the initial cover closing; and the tether being frangible to permit unthreading rotation of the cover for opening while also providing a visual indication of such opening to thereby render the container tamperproof. 